Enable hidpi on Linux, refactor a bit on Windows to share

ui/gfx/win/dpi.cc

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "ui/gfx/win/dpi.h"
-
-#include <windows.h>
-#include "base/win/scoped_hdc.h"
-#include "base/win/windows_version.h"
-#include "base/win/registry.h"
-#include "ui/gfx/display.h"
-#include "ui/gfx/point_conversions.h"
-#include "ui/gfx/rect_conversions.h"
-#include "ui/gfx/size_conversions.h"
-
-namespace {
-
-int kDefaultDPIX = 96;
-int kDefaultDPIY = 96;
-
-bool force_highdpi_for_testing = false;
-
-BOOL IsProcessDPIAwareWrapper() {
-  typedef BOOL(WINAPI *IsProcessDPIAwarePtr)(VOID);
-  IsProcessDPIAwarePtr is_process_dpi_aware_func =
-      reinterpret_cast<IsProcessDPIAwarePtr>(
-          GetProcAddress(GetModuleHandleA("user32.dll"), "IsProcessDPIAware"));
-  if (is_process_dpi_aware_func)
-    return is_process_dpi_aware_func();
-  return FALSE;
-}
-
-float g_device_scale_factor = 0.0f;
-
-float GetUnforcedDeviceScaleFactor() {
-  // If the global device scale factor is initialized use it. This is to ensure
-  // we use the same scale factor across all callsites. We don't use the
-  // GetDeviceScaleFactor function here because it fires a DCHECK if the
-  // g_device_scale_factor global is 0.
-  if (g_device_scale_factor)
-    return g_device_scale_factor;
-  return static_cast<float>(gfx::GetDPI().width()) /
-      static_cast<float>(kDefaultDPIX);
-}
-
-// Duplicated from Win8.1 SDK ShellScalingApi.h
-typedef enum PROCESS_DPI_AWARENESS {
-    PROCESS_DPI_UNAWARE = 0,
-    PROCESS_SYSTEM_DPI_AWARE = 1,
-    PROCESS_PER_MONITOR_DPI_AWARE = 2
-} PROCESS_DPI_AWARENESS;
-
-typedef enum MONITOR_DPI_TYPE {
-    MDT_EFFECTIVE_DPI = 0,
-    MDT_ANGULAR_DPI = 1,
-    MDT_RAW_DPI = 2,
-    MDT_DEFAULT = MDT_EFFECTIVE_DPI
-} MONITOR_DPI_TYPE;
-
-// Win8.1 supports monitor-specific DPI scaling.
-bool SetProcessDpiAwarenessWrapper(PROCESS_DPI_AWARENESS value) {
-  typedef BOOL(WINAPI *SetProcessDpiAwarenessPtr)(PROCESS_DPI_AWARENESS);
-  SetProcessDpiAwarenessPtr set_process_dpi_awareness_func =
-      reinterpret_cast<SetProcessDpiAwarenessPtr>(
-          GetProcAddress(GetModuleHandleA("user32.dll"),
-                          "SetProcessDpiAwarenessInternal"));
-  if (set_process_dpi_awareness_func) {
-    HRESULT hr = set_process_dpi_awareness_func(value);
-    if (SUCCEEDED(hr)) {
-      VLOG(1) << "SetProcessDpiAwareness succeeded.";
-      return true;
-    } else if (hr == E_ACCESSDENIED) {
-      LOG(ERROR) << "Access denied error from SetProcessDpiAwareness. "
-          "Function called twice, or manifest was used.";
-    }
-  }
-  return false;
-}
-
-// This function works for Windows Vista through Win8. Win8.1 must use
-// SetProcessDpiAwareness[Wrapper]
-BOOL SetProcessDPIAwareWrapper() {
-  typedef BOOL(WINAPI *SetProcessDPIAwarePtr)(VOID);
-  SetProcessDPIAwarePtr set_process_dpi_aware_func =
-      reinterpret_cast<SetProcessDPIAwarePtr>(
-      GetProcAddress(GetModuleHandleA("user32.dll"),
-                      "SetProcessDPIAware"));
-  return set_process_dpi_aware_func &&
-    set_process_dpi_aware_func();
-}
-
-DWORD ReadRegistryValue(HKEY root,
-                        const wchar_t* base_key,
-                        const wchar_t* value_name,
-                        DWORD default_value) {
-  base::win::RegKey reg_key(HKEY_CURRENT_USER,
-                            base_key,
-                            KEY_QUERY_VALUE);
-  DWORD value;
-  if (reg_key.Valid() &&
-      reg_key.ReadValueDW(value_name, &value) == ERROR_SUCCESS) {
-    return value;
-  }
-  return default_value;
-}
-
-}  // namespace
-
-namespace gfx {
-
-void InitDeviceScaleFactor(float scale) {
-  DCHECK_NE(0.0f, scale);
-  g_device_scale_factor = scale;
-}
-
-Size GetDPI() {
-  static int dpi_x = 0;
-  static int dpi_y = 0;
-  static bool should_initialize = true;
-
-  if (should_initialize) {
-    should_initialize = false;
-    base::win::ScopedGetDC screen_dc(NULL);
-    // This value is safe to cache for the life time of the app since the
-    // user must logout to change the DPI setting. This value also applies
-    // to all screens.
-    dpi_x = GetDeviceCaps(screen_dc, LOGPIXELSX);
-    dpi_y = GetDeviceCaps(screen_dc, LOGPIXELSY);
-  }
-  return Size(dpi_x, dpi_y);
-}
-
-float GetDPIScale() {
-  if (IsHighDPIEnabled()) {
-    if (gfx::Display::HasForceDeviceScaleFactor())
-      return gfx::Display::GetForcedDeviceScaleFactor();
-    float dpi_scale = GetUnforcedDeviceScaleFactor();
-    if (dpi_scale <= 1.25) {
-      // Force 125% and below to 100% scale. We do this to maintain previous
-      // (non-DPI-aware) behavior where only the font size was boosted.
-      dpi_scale = 1.0;
-    }
-    return dpi_scale;
-  }
-  return 1.0;
-}
-
-void ForceHighDPISupportForTesting(float scale) {
-  g_device_scale_factor = scale;
-}
-
-bool IsHighDPIEnabled() {
-  // Flag stored in HKEY_CURRENT_USER\SOFTWARE\\Google\\Chrome\\Profile,
-  // under the DWORD value high-dpi-support.
-  // Default is disabled.
-  static DWORD value = ReadRegistryValue(
-      HKEY_CURRENT_USER, gfx::win::kRegistryProfilePath,
-      gfx::win::kHighDPISupportW, TRUE);
-  return value != 0;
-}
-
-bool IsInHighDPIMode() {
-  return GetDPIScale() > 1.0;
-}
-
-void EnableHighDPISupport() {
-  if (IsHighDPIEnabled() &&
-      !SetProcessDpiAwarenessWrapper(PROCESS_SYSTEM_DPI_AWARE)) {
-    SetProcessDPIAwareWrapper();
-  }
-}
-
-namespace win {
-
-GFX_EXPORT const wchar_t kRegistryProfilePath[] =
-    L"Software\\Google\\Chrome\\Profile";
-GFX_EXPORT const wchar_t kHighDPISupportW[] = L"high-dpi-support";
-
-float GetDeviceScaleFactor() {
-  DCHECK_NE(0.0f, g_device_scale_factor);
-  return g_device_scale_factor;
-}
-
-Point ScreenToDIPPoint(const Point& pixel_point) {
-  return ToFlooredPoint(ScalePoint(pixel_point,
-                                   1.0f / GetDeviceScaleFactor()));
-}
-
-Point DIPToScreenPoint(const Point& dip_point) {
-  return ToFlooredPoint(ScalePoint(dip_point, GetDeviceScaleFactor()));
-}
-
-Rect ScreenToDIPRect(const Rect& pixel_bounds) {
-  // It's important we scale the origin and size separately. If we instead
-  // calculated the size from the floored origin and ceiled right the size could
-  // vary depending upon where the two points land. That would cause problems
-  // for the places this code is used (in particular mapping from native window
-  // bounds to DIPs).
-  return Rect(ScreenToDIPPoint(pixel_bounds.origin()),
-              ScreenToDIPSize(pixel_bounds.size()));
-}
-
-Rect DIPToScreenRect(const Rect& dip_bounds) {
-  // See comment in ScreenToDIPRect for why we calculate size like this.
-  return Rect(DIPToScreenPoint(dip_bounds.origin()),
-              DIPToScreenSize(dip_bounds.size()));
-}
-
-Size ScreenToDIPSize(const Size& size_in_pixels) {
-  // Always ceil sizes. Otherwise we may be leaving off part of the bounds.
-  return ToCeiledSize(
-      ScaleSize(size_in_pixels, 1.0f / GetDeviceScaleFactor()));
-}
-
-Size DIPToScreenSize(const Size& dip_size) {
-  // Always ceil sizes. Otherwise we may be leaving off part of the bounds.
-  return ToCeiledSize(ScaleSize(dip_size, GetDeviceScaleFactor()));
-}
-
-int GetSystemMetricsInDIP(int metric) {
-  return static_cast<int>(GetSystemMetrics(metric) /
-      GetDeviceScaleFactor() + 0.5);
-}
-
-bool IsDeviceScaleFactorSet() {
-  return g_device_scale_factor != 0.0f;
-}
-
-}  // namespace win
-}  // namespace gfx